Rubber robot pumps dyes into its body as camouflage

Looking like a cross between a baby octopus and a day-glo stress-relief toy, this rubber robot combines pneumatically powered movement - giving it a leisurely gait of about 40 metres per hour - with a dye-filled skin that lets it either blend in with, or stand out from, its environment.

Like its earlier rubber prototype, the robot is made to walk by pumping air through tiny channels in its legs and body. But Stephen Morin of the Whitesides Research Group at Harvard University and colleagues have now added an outer layer of capillaries through which a variety of dyes can be pumped. Depending on the choice of dye, the robot can be camouflaged or made the brightest object against a cluttered background.

(Image: S Morin,Harvard University)

By using dye that emits light via a chemical reaction - like that used in glowsticks and similar to that found in fireflies - the robot can also be made to glow in the dark.Yet another possibility is to vary the temperature of the dye along with the colour, making the robot invisible to the eye but visible in the infrared spectrum, and vice versa.

Camouflage might one day be desirable for machines that operate in public spaces - part of an unseen future infrastructure bustling invisibly around us. The potential for a surveillance bot is also there, provided its umbilical cord can be cut.

The robot is currently controlled by a human operator and tethered by tubes through which air and dye are pumped. But an autonomous version might not be too far off. For a start, a larger model that can carry bulky components such as power supplies, pumps and fluid reservoirs wouldn't need the tether, says Morin.